Rotavirus is the most common cause of severe gastroenteritis in infants causing nearly 1 million deaths worldwide and costing the United States 1.5 billion dollars annually. The only FDA-approved rotavirus vaccine was withdrawn in 1999 because of its association with bowel obstruction (intussusception). We are developing subunit rotavirus vaccines, one of which contains the powerful bacterial enterotoxin adjuvant LT(R192G). When delivered intranasally or orally in mice, this vaccine formulation induces nearly complete protection against rotavirus shedding after oral challenge. To increase the safety and ease of delivery of this candidate vaccine, we propose to compare three needle-free immunization methods at the skin using the mouse model: (1) Topical application (transcutaneous immunization) of the protein formulation, (2) Delivery of the protein formulation using a needleless injecting device, and (3) Delivery of a DNA form of the formulation using the injection device. Each delivery method will include LT(R192G). In Phase II SBIR studies, we will refine and prepare the most effective vaccine formulation for initial safety studies in humans. In Phase III SBIR studies, we will continue safety, immunogenicity and efficacy trials in humans and seek FDA approval. Successful development of VP6-based vaccines would be important for society and commercially significant.